This 5.1 MHz circuit was found in a 1980s documentation. The frequency is given by the crystal and general purpose transistors can be used.
This circuit was found in the July 1986 issue of Radio Electronics magazine. The circuit has a...
We found this electronic organ circuit in a 1987 documentation. The circuit should be powered by...
In the figure we have the basic configuration of an operational amplifier for audio signals. The...